Fiber bundle for artificial hair, and process for its production

ABSTRACT

To provide a fiber bundle for artificial hair which has a well balanced combination of properties such as bulkiness, yarn separability, weaving efficiency and hot water-curling efficiency. The fiber bundle for artificial hair is a fiber bundle obtained by crimping fibers (A) having a flexural rigidity of from 0.7 to 2.5 gf·cm 2  as measured by the KES method and has a crimp wave shape satisfying the following formula: 
       1 mm≦R≦20 mm 
     wherein R is the distance between the top and the bottom of the crimp wave shape. Further, in the fiber bundle for artificial hair, the fibers (A) are vinyl chloride fibers obtained by melt-spinning a vinyl chloride resin composition.

TECHNICAL FIELD

The present invention relates to a fiber bundle for artificial hair tobe used for head decoration, particularly to a fiber bundle forartificial hair suitable for braids.

BACKGROUND ART

Among fiber bundles for artificial hair to be used for head decoration,such as wigs, weaves, hair pieces, braids, extension hairs, accessoryhairs, etc., a fiber bundle for artificial hair to be used for braids isrequired to have a special performance for the purpose of its use.

A braid, e.g. one having crimping applied by gear-crimping, may be woveninto hair at a beauty shop or the like, and further, depending upon thestyle, curling may be imparted by hot water to complete the decoration.

Fibers for doll hair have been proposed as fibers having bulky crimpingapplied (Patent Document 1). However, such fibers for doll hair are notone having a good balance of properties required for a braid.

Patent Document 1: JP-A-11-309275

DISCLOSURE OF THE INVENTION Object to be Accomplished by the Invention

It is an object of the present invention to provide a fiber bundle forartificial hair having a well balanced combination of properties such asbulkiness, yarn separability, weaving efficiency and hot water-curlingefficiency.

Means to Accomplish the Object

The present inventors have conducted an extensive study to accomplishthe above object and as a result, have found it possible to obtain afiber bundle for artificial hair having a well balanced combination ofproperties such as bulkiness, yarn separability, weaving efficiency andhot water-curling efficiency by applying crimping under the followingconditions to fibers (A) having a flexural rigidity of from 0.7 to 2.5gf·cm² as measured by the KES method.

That is, the present invention provides the following.

(1) A fiber bundle for artificial hair, which is a fiber bundle obtainedby crimping fibers (A) having a flexural rigidity of from 0.7 to 2.5gf·cm² as measured by the KES method and which has a crimp wave shapesatisfying the following formula:

1 mm≦R≦20 mm

wherein R is the distance between the top and the bottom of the crimpwave shape.(2) The fiber bundle for artificial hair according to the above (1),wherein the fibers (A) have a fineness of monofilament of from 20 to 100decitex.(3) The fiber bundle for artificial hair according to the above (1) or(2), wherein the fibers (A) are vinyl chloride fibers obtained bymelt-spinning a vinyl chloride resin composition.(4) The fiber bundle for artificial hair according to the above (3),wherein the vinyl chloride resin composition comprises a vinyl chlorideresin and from 0.5 to 10 parts by mass, per 100 parts by mass of thevinyl chloride resin, of a chlorinated vinyl chloride resin.(5) The fiber bundle for artificial hair according to the above (4),which further contains a thermal stabilizer.(6) The fiber bundle for artificial hair according to the above (5),wherein the thermal stabilizer is at least one member selected from thegroup consisting of a Ca—Zn type thermal stabilizer, a hydrotalcite typethermal stabilizer, a tin type thermal stabilizer and a zeolite typethermal stabilizer.(7) The fiber bundle for artificial hair according to any one of theabove (1) to (6), wherein the cross-sectional shape of the fibers (A) isa Y-shape, a H-shape, a U-shape, a C-shape or a X-shape.(8) The fiber bundle for artificial hair according to any one of theabove (1) to (7), wherein the crimping is gear-crimping.(9) The fiber bundle for artificial hair according to any one of theabove (1) to (8), which is for head decoration.(10) A braid using the fiber bundle for artificial hair as defined inthe above (9).(11) A process for producing a fiber bundle for artificial haircomprising the following sequential steps (a) to (e):

(a) a step of mixing a vinyl chloride resin composition comprising avinyl chloride resin and a thermal stabilizer,

(b) a step of melt-spinning the vinyl chloride resin composition from aspinneret at a spinneret temperature of from 160 to 190° C.,

(c) a step of stretching the melt-spun fibers (A) in an atmosphere at astretching temperature of from 90 to 120° C. at a stretching ratio offrom 200 to 400%.

(d) a step of subjecting the stretched fibers (A) to thermal relaxingtreatment in an atmosphere of air at a temperature of from 110 to 140°C. until the entire length of the fibers becomes from 60 to 95% of thelength before the treatment, and

(e) a step of gear-crimping the fibers (A) treated for thermal relaxing,at a gear surface temperature of from 30 to 100° C. at a crimping rateof from 0.5 to 10 m/min.

EFFECTS OF THE INVENTION

According to the present invention, it is possible to obtain a fiberbundle for artificial hair having a well balanced combination ofproperties such as bulkiness, yarn separability, weaving efficiency andhot water-curling efficiency.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view illustrating a crimp wave shape of the fiberbundle for artificial hair of the present invention.

MEANING OF SYMBOL

R: Distance between the top and the bottom of the crimp wave shape

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, crimping means, for example, gear-crimping tocontinuously impart a wave form by sandwiching fibers between two gearrolls, or a method to impart a wave shape by continuously pushing fibersheated by e.g. steam into e.g. a stuffing box. By such a method, a waveform suitable for the desired product is imparted, whereby theprocessability into braids, extension hairs, etc. will be improved, andit is possible to obtain a fiber bundle for artificial hair having thegloss of fibers properly adjusted.

Gear-crimping is a method to apply crimping by passing the fiber bundlebetween two meshing high temperature gears, wherein the material ofgears to be used, the wave shape and size of gears, the number of gearteeth, etc. are not particularly limited. The crimp wave shape may bechanged by the material or fineness of fibers, the pressure conditionbetween the gears, etc.

In the present invention, the crimp wave shape can be controlled by thegear surface temperature or the crimping rate. These crimping conditionsare not particularly limited, but the gear surface temperature ispreferably from 30 to 100° C., more preferably from 40 to 80° C., andthe crimping rate is preferably from 0.5 to 10 m/min, more preferablyfrom 1.0 to 8.0 m/min. If the gear surface temperature is lower than 30°C., the crimping tends to be weak, and a crimp wave shape may notsometimes be imparted. On the other hand, if the gear surfacetemperature exceeds 100° C., the crimping is likely to be imparted somuch that R in the crimp wave shape tends to be large. If the crimpingrate is less than 0.5 m/min, R in the crimp wave shape may sometimes belarge. On the other hand, if the crimping rate exceeds 10 m/min, thecrimping is likely to be weak, and no adequate crimp wave shape maysometimes be imparted.

On the other hand, it is preferred to apply preheating to the fiberbundle before passing it through the gears, whereby a more stabilizedproductivity and a more uniform crimp wave shape may be obtained. Ifcrimping is intensive, bulkiness and weaving efficiency may be good, butyarn separability tends to deteriorate. On the other hand, if thecrimping is weak, yarn separability may be good, but the bulkiness andweaving efficiency tend to deteriorate.

At the time of gear-crimping, the total fineness of the fiber bundle isnot particularly limited, but is preferably from 100,000 to 2,000,000decitex, more preferably from 500,000 to 1,500,000 decitex. If the totalfineness of the fiber bundle is less than 100,000 decitex, theproductivity in gear-crimping tends to be poor, and yarn breakage mayresult by the gear-crimping. On the other hand, if the total fineness ofthe fiber bundle exceeds 2,000,000 decitex, it tends to be difficult toobtain a uniform crimp wave shape.

In the fiber bundle for artificial hair of the present invention, thecrimp wave shape shown in FIG. 1 satisfies the following formula:

1 mm≦R≦20 mm

wherein R is the distance between the top and the bottom of the crimpwave shape.

The distance R in the crimp wave shape is from 1 to 20 mm, preferablyfrom 3 to 15 mm. If the distance R in the crimp wave shape is less than1 mm, no adequate effect of gear-crimping will be obtained, whereby thebulkiness tends to be small, and further, intertwining among fibers inthe fiber bundle tends to be little, and fibers tend to be slippery oneanother, thus leading to poor weaving efficiency. On the other hand, ifR exceeds 20 mm, the crimp wave shape tends to be rough, and fibers tendto be caught by figures when they are to be separated, whereby the yarnseparability tends to be poor.

In the present invention, the KES method is an abbreviation of Kawabataevaluation system and is one to measure the repulsive forces at variouscurvatures when a fiber structure is bent by means of a KES flexuralproperty-measuring machine (manufactured by KATO TECH CO., LTD), asdisclosed by Tokio Kawabata in the Journal of the Textile MachinerySociety of Japan (Textile Engineering), vol. 26, No. 10, p 721-728(1973). And, an average value of repulsive forces of monofilament withina curvature ranges of from 0.5 to 1.5 cm⁻¹, is measured. By measuringthe repulsive force by monofilament, the rigidity of the fiber bundlecan be predicted.

A method of controlling the flexural rigidity value by the KES methodcan be attained, for example, by controlling the spinneret temperatureat the time of the melt-spinning.

Although the reason is not clearly understood, the flexural rigidity canbe made low by lowering the spinneret temperature. The control of theflexural rigidity can also be attained by changing the monofilamentfineness of the fibers. By reducing the monofilament fineness, theflexural rigidity can be made low. Further, in the case of a crosssectional shape with high bulkiness, the flexural rigidity tends to behigh, and in the case of a cross sectional shape with low bulkiness, theflexural rigidity tends to be low. The cross sectional shape with highbulkiness may, for example, be a Y-shape, a H-shape, a U-shape, aC-shape or a X-shape. The cross sectional shape with low bulkiness may,for example, be an elliptical, circular or cocoon shape.

Here, with respect to the cross sectional shape, the Y-shape is a shaperesembling alphabetical letter Y with an axis divided into threedirections as viewed in its cross section; the H-shape is a shaperesembling alphabetical letter H as viewed in its cross section; theU-shape is a shape resembling alphabetical letter U as viewed in itscross section; the C-shape is a shape resembling alphabetical letter Cwith the circumferential surface of a thin-walled cylindrical fiberpartly cut out in the longitudinal direction, as viewed in its crosssection; the X-shape is a shape resembling alphabetical letter X withradially extending four protrusions as viewed in its cross section;elliptical is an oval shape as viewed in its cross section; circular isa circular shape as viewed in its cross section; and the cocoon shape isa shape resembling the shape of a cocoon formed by a combination of twocylinders extending in parallel as viewed in its cross section.

The flexural rigidity per fiber as measured by the KES method is from0.7 to 2.5 gf·cm², preferably from 1.0 to 2.0 gf·cm². If the flexuralrigidity as measured by the KES method is less than 0.7 gf·cm², therigidity to maintain curling tends to be inadequate, whereby thecurl-retention performance tends to be poor, and the hot water-curlingefficiency tends to be deteriorated. On the other hand, if the flexuralrigidity as measured by the KES method exceeds 2.5 gf·cm², the rigiditytends to be so high that the fibers tend to have a hard touch, and theweaving efficiency tends to be deteriorated. The cross sectional shapeof the fibers (A) having a flexural rigidity of from 0.7 to 2.5 gf·cm²as measured by the KES method, is preferably a Y-shape, a H-shape, aU-shape, a C-shape or a X-shape. Such a cross sectional shape has a highsymmetry and, with the same fineness, has a relatively larger porositythan e.g. a circular cross sectional shape, whereby the rigidity ishigh, and it is suitable for obtaining more uniform curling efficiency.

In a case where a soft touch is more important for the fiber bundle forartificial hair of the present invention, a fiber bundle for artificialhair is preferred which has a flexural rigidity of from 0.7 to less than1.4 gf·cm² as measured by the KES method and which satisfies that thedistance R in the crimp wave shape is within a range of less than from 1to 4 mm. Further, in a case where the bulkiness is more important, afiber bundle for artificial hair is preferred which has a flexuralrigidity of from 1.4 to less than 2.5 gf·cm² as measured by the KESmethod and which satisfies that the distance R in the crimp wave shapeis within a range of from 4 to less than 20 mm.

In the present invention, the fibers (A) preferably have a fineness ofmonofilament of from 20 to 100 decitex, more preferably from 35 to 80decitex. If the fineness of monofilament is less than 20 decitex, suchfibers tend to be so soft that their stiffness tends to be inadequate,but also they tend to be poor in the retention of the crimp wave shape,and their commercial value is likely to be low. On the other hand, ifthe fineness of monofilament exceeds 100 decitex, the flexural rigiditytends to be large whereby the texture will be rough and hard, and theweaving efficiency is likely to be poor. The rigidity varies dependingupon the material and cross sectional shape of the fibers, and theoptimum fineness should be selected for each material.

In the present invention, the synthetic resin which may be used as thefibers (A), includes all synthetic resins which can be formed intofibers, such as a vinyl chloride resin, a modacrylic resin, an acrylicresin, a polyethylene terephthalate resin, a polypropylene resin, anylon resin, a polylactic acid type resin and a polyvinyl alcohol resin.Among them, a vinyl chloride resin is particularly preferred in view ofthe properties such as the strength, gloss, color hue, flame retardancy,touch, thermal shrinkage property, etc.

The vinyl chloride resin to be used in the present invention, may be oneobtained by bulk polymerization, solution polymerization, suspensionpolymerization, emulsion polymerization or the like. However, it ispreferred to use one produced by suspension polymerization, inconsideration of e.g. the initial coloration of the fibers.

The vinyl chloride resin is not particularly limited and may be aconventional homopolymer of vinyl chloride or conventional various typesof copolymer resins. As such a copolymer resin, a conventional copolymerresin may be used, and typical examples include a copolymer resin ofvinyl chloride with a vinyl ester, such as a vinyl chloride/vinylacetate copolymer resin or a vinyl chloride/vinyl propionate copolymerresin; a copolymer resin of a vinyl chloride with an acrylate, such as avinyl chloride/butyl acrylate copolymer resin or a vinylchloride/2-ethylhexyl acrylate copolymer resin; a copolymer resin ofvinyl chloride with an olefin, such as a vinyl chloride/ethylenecopolymer resin or a vinyl chloride/propylene copolymer resin; and avinyl chloride/acrylonitrile copolymer resin. It is particularlypreferred to use, for example, a homopolymer resin as a homopolymer ofvinyl chloride, a vinyl chloride/ethylene copolymer resin or a vinylchloride/vinyl acetate copolymer resin. In such a copolymer resin, thecontent of the vinyl chloride comonomer is not particularly limited andmay be determined depending upon the required quality such as themolding processability, yarn properties, etc. Particularly preferably,the content of the vinyl chloride comonomer is from 2 to 30%, morepreferably from 2 to 20%.

The viscosity-average polymerization degree of the vinyl chloride resinto be used in the present invention is preferably from 600 to 2,500,more preferably from 600 to 1,800. If the viscosity-averagepolymerization degree is less than 600, the melt viscosity tends to below, and the obtained fibers are likely to be susceptible to heatshrinkage. On the other hand, if it exceeds 2,500, the melt viscositybecomes high, and the nozzle pressure becomes high, whereby safeproduction tends to be difficult. Here, the viscosity-averagepolymerization degree is one obtained by dissolving 200 mg of the resinin 50 ml of nitrobenzene and measuring the specific viscosity of thispolymer solution in a 30° C. constant temperature tank by means of anUbbelohde viscometer, followed by calculation in accordance with JISK6720-2.

In the present invention, a chlorinated vinyl chloride resin is furtherincorporated, whereby slippage of fibers of the fiber bundle from oneanother can be suppressed, and the weaving efficiency at the time ofprocessing into a braid may, for example, be improved.

With respect to the content of the chlorinated vinyl chloride resin, thechlorinated vinyl chloride resin is preferably from 0.5 to 10 parts bymass, more preferably from 1 to 5 parts by mass, per 100 parts by massof the vinyl chloride resin. If the chlorinated vinyl chloride resin isless than 0.5 part by mass, the effect to suppress slippage of fibers ofthe fiber bundle from one another tends to be small. On the other hand,if the chlorinated vinyl chloride resin exceeds 10 parts by mass, thesurface roughness of the obtained fibers (A) tends to be high, wherebythe texture tends to be hard, and it is likely to damage hands at thetime of weaving the fiber bundle, and thus the weaving efficiency tendsto be poor.

The viscosity-average polymerization degree of the chlorinated vinylchloride resin to be used in the present invention is preferably from450 to 800, more preferably from 500 to 600. If the viscosity-averagepolymerization degree is less than 450, the melt viscosity tends to below, and the obtained fibers (A) are likely to be susceptible to heatshrinkage. On the other hand, if it exceeds 800, the melt viscositytends to be high, and the nozzle pressure tends to be high, whereby safeproduction is likely to be difficult. Here, the viscosity-averagepolymerization degree is one calculated by the same method as describedabove.

The vinyl chloride resin composition of the present invention maycontain known additives which are commonly used for a vinyl chlorideresin composition, depending upon the particular purpose. The additivesmay, for example, be a thermal stabilizer, a plasticizer, a lubricant, acompatibilizing agent, a processing aid, a reinforcing agent, anultraviolet absorber, an antioxidant, an antistatic agent, a filler, aflame retardant, a pigment, an initial coloration-improving agent, anelectrical conductivity-imparting agent, a surface treating agent, aphotostabilizer and a perfume.

As the thermal stabilizer to be used in the present invention, aconventional one may be used. Particularly, it is preferred to use atleast one member selected from the group consisting of a Ca—Zn typethermal stabilizer, a hydrotalcite type thermal stabilizer, a tin typethermal stabilizer and a zeolite type thermal stabilizer. Such a thermalstabilizer is used to prevent thermal decomposition during the moldingor to improve the color of fibers and long-run properties. It isparticularly preferred to use a Ca—Zn type thermal stabilizer and ahydrotalcite type thermal stabilizer in combination, whereby the balanceof the molding processability and yarn properties is excellent. Such athermal stabilizer is used in an amount of preferably from 0.1 to 5.0parts by mass, more preferably from 0.3 to 3.0 parts by mass, per 100parts by mass of the vinyl chloride resin.

The hydrotalcite type thermal stabilizer is specifically a hydrotalcitecompound, and more specifically, it may be a composite salt compoundcomprising magnesium and/or an alkali metal, and aluminum, or zinc,magnesium and aluminum, and may be one having crystal water dehydrated.The hydrotalcite compound may be natural one or synthesized one. Themethod for preparing a synthesized product may be a conventional method.

The fibers (A) and the fiber bundle for artificial hair of the presentinvention are produced by carrying out the following steps (a) to (e)sequentially:

(a) a step of mixing a vinyl chloride resin composition comprising avinyl chloride resin and a thermal stabilizer,

(b) a step of melt-spinning the vinyl chloride resin composition from aspinneret at a spinneret temperature of from 160 to 190° C.,

(c) a step of stretching the melt-spun fibers (A) in an atmosphere at astretching temperature of from 90 to 120° C. at a stretching ratio offrom 200 to 400%.

(d) a step of subjecting the stretched fibers (A) to thermal relaxingtreatment in an atmosphere of air at a temperature of from 110 to 140°C. until the entire length of the fibers becomes from 60 to 95% of thelength before the treatment, and

(e) a step of gear-crimping the fibers (A) treated for thermal relaxing,at a gear surface temperature of from 30 to 100° C. at a crimping rateof from 0.5 to 10 m/min.

In the step (a) of mixing the vinyl chloride resin composition of thepresent invention comprising a vinyl chloride resin and a thermalstabilizer, a conventional mixing machine such as a Henschel mixer, asupermixer or a ribbon blender may, for example, be used. The mixedvinyl chloride resin composition can be used as a powder compound or apellet compound obtained by melt-kneading the powder compound.

The powder compound can be produced under conventional usual conditions.Either hot blending or cold blending may be used, but it is preferred touse hot blending by raising the resin temperature at the time ofblending to a level of from 105 to 155° C., preferably from 105 to 135°C., in order to reduce the volatile content in the vinyl chloride resincomposition.

The pellet compound can be produced in the same manner as in a usualproduction of a vinyl chloride pellet compound. For example, a pelletcompound may be made by using a kneading machine such as a single screwextruder, a counter-rotating twin screw extruder, a conical twin screwextruder, a corotating twin screw extruder, a cokneader, a planetarygear extruder or a roll kneader. The conditions for producing the pelletcompound are not particularly limited, but it is preferred to set theresin temperature to be at most 185° C., preferably at most 180° C. Itis optionally possible to install a stainless steel mesh or the likehaving a fine aperture in the kneading machine to remove foreign matterswhich may be included in the pellet compound, to employ a means toremove “chips”, etc. which may be included during cold cutting, or tocarry out hot cutting. Particularly preferably a hot cutting method maybe used which is substantially free from inclusion of “chips”.

A conventional extruder may be used to form the vinyl chloride resincomposition into a non-stretched fiber yarn. For example, a single screwextruder, a counter-rotating twin screw extruder or a conical twin screwextruder may, for example, be used. It is particularly preferred to usea single screw extruder having a bore diameter of from 35 to 85 mm or aconical twin screw extruder having a bore diameter of from about 35 to50 mm. If the bore diameter is excessively large, the extrusion amounttends to be large, and the nozzle pressure tends to be too large, or theflow-out speed of the non-stretched yarn tends to be so high thatwinding tends to be difficult, such being undesirable.

Now, with respect to the step (b) of melt-spinning the vinyl chlorideresin composition in the present invention, the fineness of monofilamentof the non-stretched yarn is preferably adjusted to be at most 300decitex, more preferably at most 250 decitex. If the fineness of thenon-stretched yarn exceeds 300 decitex, it will be required to increasethe stretching ratio at the time of the stretching treatment in order toobtain the fibers (A) having fine fineness, and the fibers (A) havingfine fineness after the stretching treatment will be glossy, whereby ittends to be difficult to maintain the level of a medium gloss to 70%gloss state.

Further, at the time of melt-spinning, it is preferred to carry outspinning under a nozzle pressure of at most 50 MPa, preferably at most45 MPa. If the nozzle pressure exceeds 50 MPa, the load exerted to athrust portion of the extruder tends to be excessive, whereby a troubleof the extruder is likely to occur. Further, “a resin leakage” is likelyto result at a portion connected to the turn head, the die, etc.

In the present invention, the melt-spinning can be carried out byattaching to the forward end portion of the die (spinneret), nozzleshaving, for example, a C-shape in cross section similar to the crosssectional shape C of the fibers (A).

When the quality aspect such as the curling property as a fiber bundlefor head decoration is taken into consideration, it is preferred toproduce a non-stretched yarn having a fineness of monofilament of atmost 300 decitex by having the vinyl chloride resin composition meltedand extruded in the form of strands from multi type nozzle holes (numberof nozzle holes is from 50 to 300, preferably from 60 to 280, and numberof nozzle rows is from 1 to 5, preferably from 2 to 5) where a pluralityof nozzle holes each having a cross sectional area of at most 0.5 mm²,are arranged in rows in the die. Specifically, a pellet compound or thelike of a resin composition is melt-spun, for example, by means of asingle screw extruder at a spinneret temperature of from 160 to 190° C.,more preferably from 165 to 185° C., whereby a non-stretched yarn isobtainable.

Further, in the step (c) of stretching the melt-spun fibers (A), thenon-stretched yarn obtained by the above melt spinning is subjected tostretch treatment/thermal treatment by a known method to obtain fibers(stretched yarn) having a fineness of at most 100 decitex. With respectto the conditions for the stretching treatment, stretching is carriedout in an atmosphere at a stretching treatment temperature of from 90 to120° C., preferably from 95 to 115° C. at a stretching ratio of fromabout 200 to 400%, preferably from about 220 to 360%. If the stretchingtreatment temperature is lower than 90° C., the strength of the fiberstend to be low, and yarn breakage is likely to occur. On the other hand,if it exceeds 120° C., the texture of the fibers tends to be a slipperytexture like plastics, such being undesirable. Whereas, if thestretching ratio is less than 200%, development of the strength offibers tends to be inadequate, and if it exceeds 400%, yarn breakage islikely to occur during the stretching treatment, such being undesirable.

Further, the step (d) of subjecting the stretched fibers (A) to thermalrelaxing treatment is carried out.

The stretched fibers (A) is subjected to thermal relaxing treatment inan atmosphere of air maintained at a temperature of from 110 to 140° C.,preferably from 115 to 135° C. until the length becomes from 60 to 100%,preferably from 65 to 90%, of the length before the thermal relaxingtreatment, whereby the thermal shrinkage can be lowered. Such thermalrelaxing treatment may be carried out continuously or separately fromthe stretching treatment.

Thereafter, the fibers (A) treated for thermal relaxing are subjected tothe step (e) of gear-crimping at a gear surface temperature of from 30to 100° C., preferably from 40 to 90° C., at a processing rate of from0.5 to 10 m/min, preferably from 0.8 to 8 m/min. As the material forgears, not only brass, but also iron, copper, stainless steel or thelike, may be used. Particularly preferred is brass or iron.

Further, in the present invention, conventional techniques relating tomelt-spinning, such as techniques relating to various nozzle crosssectional shapes, techniques relating to heating cylinders, techniquesrelating to stretching treatment, techniques relating to thermaltreatment, etc., may be used freely in combination.

When the fiber bundle for artificial hair of the present invention isincorporated in the total fibers in an amount of at least 90%,preferably at least 95%, of the total number of fibers, it is possibleto obtain a fiber bundle for head decoration including one for a braidor one for extension hair excellent in handling efficiency in manualoperation.

The fiber bundle for artificial hair of the present invention is one tobe used for hair decoration such as a hair pieces, a braid, an extensionhair or a doll hair. However, the fiber bundle subjected to crimpingsuch as gear crimping is particularly suitable for a braid, an extensionhair or the like among various hair decorations.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples and Comparative Examples. However, it should beunderstood that the present invention is by no means thereby restricted,since such Examples and Comparative Examples are merely exemplary.

TABLE 1 Examples Comparative Examples 1 2 3 4 5 6 7 1 2 3 4 R (mm) 8 215 8 8 8 8 0.5 25 8 8 Flexural rigidity 1.6 1.6 1.6 1.2 2.2 1.6 1.6 1.61.6 0.7 2.8 (gf/cm²) Nozzle shape X-shape X-shape X-shape H-shapeC-shape X-shape X-shape X-shape X-shape Elliptical C-shape Fineness of67 67 67 67 67 67 67 67 67 67 89 monofilament (decitex) Resin Vinyl 100100 100 100 100 100 100 100 100 100 100 chloride resin (parts) Chlori- 00 0 0 0 3 15 0 0 0 0 nated vinyl chloride resin (parts) Specific volumeExcellent Good Excellent Excellent Excellent Excellent Excellent No goodExcellent Excellent Excellent (cc/g) 23 16 29 22 23 23 25 10 35 21 22Combing Excellent Excellent Good Excellent Excellent Excellent ExcellentExcellent No good Excellent Excellent efficiency Weaving Good Good GoodGood Good Excellent Good No good Excellent Excellent No good efficiencyCurl retention Excellent Excellent Excellent Good Excellent ExcellentExcellent Excellent Excellent No good Excellent (cm) 0.7 0.5 0.7 1.3 0.30.6 0.6 0.5 0.8 1.8 0.2

In Table 1, “Flexural rigidity” was measured by KES (Kawabata evaluationsystem)-FB2 pure bending testing machine (manufactured by KATO TECH CO.,LTD). The sample was one fiber having a length of 9 cm, and it waspassed through a jig having a diameter of 0.2 μm, whereupon a purebending test was carried out at a deformation speed of 0.2 cm⁻¹ within acurvature range of −2.5 to +2.5 cm⁻¹, and an average value of repulsionforces with a monofilament within a curvature range of from 0.5 to 1.5cm⁻¹, was measured.

In Table 1, “Specific volume” is an index for bulkiness of fibers. Inthe method for measuring the specific volume, fibers cut in a length of100 mm and gear-crimped, were filled in a 56 cc container (100 mm×14mm×40 mm) until the container became full, and the filled fibers weretaken out and measured, whereupon the specific volume was calculated bythe following formula and evaluated by the following evaluationstandards.

Volume (cc) of container÷weight (g) of fibers=specific volume (cc/g)

Excellent: One having a specific volume of at least 20.0 (cc/g) andhaving very high bulkiness.

Good: One having a specific volume of from 15.0 to less than 20.0 (cc/g)and having high bulkiness.

No good: One having a specific volume of less than 15.0 (cc/g) andhaving low bulkiness.

In Table 1, “Combing efficiency” is an index for yarn separability atthe time of weaving. 50 g of gear-crump fibers cut in a length of 1 mwere taken and combed by a dog brush, whereby yarn breakage was observedfor judgment. The less the yarn breakage, the smoother the combing, andthe better the yarn separability. The evaluation was made by thefollowing standards.

Excellent: One free from yarn breakage and excellent in combingefficiency.

Good: One having no problem with respect to the working efficiency andproduct quality although some yarn breakage is observed.

No good: Substantial number of yarn breakage is observed, and theoperation efficiency at the time of weaving is poor.

In Table 1, “Weaving efficiency” is an index representing easiness inweaving. The weaving efficiency was evaluated from the degree ofcrimping under the following evaluation standards based on judgment byten technicians (with practical experience of at least 5 years) fortreatment of fibers for artificial hair.

Excellent: One evaluated by all of the technicians to be easy forweaving and thus being excellent in weaving efficiency.

Good: One evaluated by at least 80% of technicians to be easy forweaving and thus being good in weaving efficiency.

No good: One evaluated by at least 30% of technicians to be difficultfor weaving and thus being poor in weaving efficiency.

In Table 1, “Curl retention” is an index representing hot water-curlingefficiency. One gram of a fiber bundle having a length of 30 cm waswound on an aluminum pipe having a diameter of 20 mm and its forward endwas fixed, and in that state, immersed in hot water at 80° C. for 15seconds. Then, it was taken out and hanged in a state where thetemperature was 23° C. and the humidity was 50%, for 24 hours, wherebythe moving distance of the forward end between before and after thehanging was measured. The shorter the moving distance, the better thecurling retention, thus representing that curling was properly exertedby hot water-treatment. The evaluation was made by the followingevaluation standards.

Excellent: The moving distance is less than 1.0 cm.

Good: The moving distance is at least 1.0 cm and less than 1.5 cm.

No good: The moving distance is at least 1.5 cm.

Example 1

Vinyl chloride type fibers (A) having the fineness of monofilament andthe numerical value of the flexural rigidity as shown in Table 1 wereobtained by sequentially carrying out (a) a step of mixing by a Henschelmixer a vinyl chloride resin composition prepared by blending 100 partsby mass of a vinyl chloride resin (TH-1000, manufactured by TAIYO VINYLCORP., viscosity average polymerization degree: 1030, apparent density:0.54), 3 parts by mass of a hydrotalcite type composite stabilizer(CP-410A, manufactured by Nissan Chemical Industries, Ltd.) (thermalstabilizer component: 1.5 parts by mass), 0.5 part by mass of anepoxidized soybean oil (O-130P, manufactured by Asahi Denka Kogyo K.K.)and 0.8 part by mass of an ester lubricant (EW-100, manufactured byRiken Vitamin Co., Ltd.), (b) a step of melt-spinning the mixed resincomposition by means of a spinneret having 120 nozzle holes with anX-form nozzle shape and a nozzle cross sectional area of 0.06 mm² at aspinneret temperature of 170° C. at an extrusion rate of 10 kg/hr toobtain fibers with 150 decitex, (c) a step of stretching the melt-spunfibers 300% in an atmosphere of air at 100° C., and (d) a step ofsubjecting the stretched fibers to thermal relaxing treatment in anatmosphere of air at 120° C. until the entire length of fibers shrank toa length of 75% of the length before the treatment. Then, the fibers (A)were formed into a fiber bundle having a total fineness of 1,000,000decitex and subjected to (e) a step of gear-crimping it by means ofgears made of brass (diameter: 13 cm, distance between gear waves: 6 mm,depth of gear waves: 7 mm) at a gear surface temperature of 50° C. at aprocessing rate of 2.5 m/min. As a result, a fiber bundle for artificialhair was obtained which had the numerical value of R (the distancebetween the top and the bottom of the crimp wave shape) as shown inTable 1.

Examples 2 and 3

A fiber bundle for artificial hair was obtained in the same manner as inExample 1 except that the processing conditions for the gear-crimping inExample 1 were changed to obtain the numerical value of R as shown inTable 1.

Examples 4 and 5

A fiber bundle for artificial hair was obtained in the same manner as inExample 1 except that the nozzle shape in the step (b) in Example 1 waschanged to a H-shape in Example 4, or to a C-shape in Example 5, toobtain the flexural rigidity as shown in Table 1.

Examples 6 and 7

A fiber bundle for artificial hair was obtained in the same manner as inExample 1 except that in the step (a) in Example 1, the chlorinatedvinyl chloride resin (HA-15E, manufactured by TAIYO VINYL CORP.) waschanged to have the content as shown in Table 1.

Comparative Examples 1 and 2

A fiber bundle for artificial hair was obtained in the same manner as inExample 1 except that the processing conditions for the gear-crimping inExample 1 were changed to have the numerical value of R as shown inTable 1.

Comparative Examples 3 and 4

A fiber bundle for artificial hair was obtained in the same manner as inExample 1 except that melt-spinning was carried out by changing thenozzle shape in the step (b) in Example 1 to elliptical in ComparativeExample 3, or to a C-shape in Comparative Example 4 to have a finenessof 200 decitex, and the flexural rigidity and the fineness ofmonofilament were as shown in Table 1.

As is evident from Table 1, by the present invention, it is possible toobtain a fiber bundle for artificial hair which has a well balancedcombination of properties such as bulkiness, yarn separability, weavingefficiency and hot water-curling efficiency.

INDUSTRIAL APPLICABILITY

The fiber bundle for artificial hair of the present invention has a wellbalanced combination of properties such as bulkiness, yarn separability,weaving efficiency and hot water-curling efficiency and thus is suitablefor hair decoration such as a braid.

The entire disclosure of Japanese Patent Application No. 2006-337831filed on Dec. 15, 2006 including specification, claims, drawings andsummary is incorporated herein by reference in its entirety.

1. A fiber bundle for artificial hair, which is a fiber bundle obtainedby crimping fibers (A) having a flexural rigidity of from 0.7 to 2.5gf·cm² as measured by the KES method and which has a crimp wave shapesatisfying the following formula:1 mm≦R≦20 mm wherein R is the distance between the top and the bottom ofthe crimp wave shape.
 2. The fiber bundle for artificial hair accordingto claim 1, wherein the fibers (A) have a fineness of monofilament offrom 20 to 100 decitex.
 3. The fiber bundle for artificial hairaccording to claim 1, wherein the fibers (A) are vinyl chloride fibersobtained by melt-spinning a vinyl chloride resin composition.
 4. Thefiber bundle for artificial hair according to claim 3, wherein the vinylchloride resin composition comprises a vinyl chloride resin and from 0.5to 10 parts by mass, per 100 parts by mass of the vinyl chloride resin,of a chlorinated vinyl chloride resin.
 5. The fiber bundle forartificial hair according to claim 4, which further contains a thermalstabilizer.
 6. The fiber bundle for artificial hair according to claim5, wherein the thermal stabilizer is at least one member selected fromthe group consisting of a Ca—Zn type thermal stabilizer, a hydrotalcitetype thermal stabilizer, a tin type thermal stabilizer and a zeolitetype thermal stabilizer.
 7. The fiber bundle for artificial hairaccording to claim 1, wherein the cross-sectional shape of the fibers(A) is a Y-shape, a H-shape, a U-shape, a C-shape or a X-shape.
 8. Thefiber bundle for artificial hair according to claim 1, wherein thecrimping is gear-crimping.
 9. The fiber bundle for artificial hairaccording to claim 1, which is for head decoration.
 10. A braid usingthe fiber bundle for artificial hair as defined in claim
 9. 11. Aprocess for producing a fiber bundle for artificial hair comprising: (a)mixing a vinyl chloride resin composition comprising a vinyl chlorideresin and a thermal stabilizer, (b) melt-spinning the vinyl chlorideresin composition from a spinneret at a spinneret temperature of from160 to 190° C., (c) stretching the melt-spun fibers (A) in an atmosphereat a stretching temperature of from 90 to 120° C. at a stretching ratioof from 200 to 400%. (d) subjecting the stretched fibers (A) to thermalrelaxing treatment in an atmosphere of air at a temperature of from 110to 140° C. until the entire length of the fibers becomes from 60 to 95%of the length before the treatment, and (e) gear-crimping the fibers (A)treated for thermal relaxing, at a gear surface temperature of from 30to 100° C. at a crimping rate of from 0.5 to 10 m/min, wherein (a) to(e) occur sequentially.
 12. The fiber bundle for artificial hairaccording to claim 5, wherein the thermal stabilizer is at least onemember selected from the group consisting of a Ca—Zn thermal stabilizer,a hydrotalcite thermal stabilizer, a tin thermal stabilizer and azeolite thermal stabilizer.
 13. The fiber bundle for artificial hair asdefined in claim 9, in the form of a braid.